BACKGROUNDThe regioselective hydration of alicyclic ,-dinitrile 1-cyanocyclohexaneacetonitrile (1-CCHAN), followed by hydrogenation of -cyano group is a green and elegant route to gabapentin. As the selective chemical hydration of dinitrile is virtually impossible, a bioprocess for regioselective hydration of 1-CCHAN was developed using microbial nitrile hydratase. RESULTSA newly isolated NHase producing strain, Rhodococcus aetherivoransZJB1208, was successfully used for hydration of 1-CCHAN. Some key parameters of the biocatalytic process, including reaction temperature, pH, catalyst loading and substrate loading, were optimized. The fed-batch biotransformation was performed in non-buffered water system with the continuous precipitation of 1-cyanocyclohexaneacetamide. The substrate loading was increased up to 864 g L-1 (6.0 mol L-1), giving a product concentration of 966.7 g L-1 and biocatalyst yield (g(product)/g(cat)) of 204.2. CONCLUSIONThis study is the first example of microbial nitrile hydratase with both excellent regioselectivity and strong substrate tolerance for alicyclic dinitrile and affords a potentially industrial route to gabapentin. (c) 2015 Society of Chemical Industry